Dependence of grain size on the substrate temperature of Si and Ge films prepared by evaporation under ultrahigh vacuum

Silicon and germanium films were evaporated in ultrahigh vacuum at substrate temperatures ranging from 0 to 600 °C, and this was followed by high-temperature annealing. The grain size of the annealed microcrystalline samples was measured by transmission electron microscopy. The maximum grain size occurs when the substrate temperature is in the range in which the deposited film changes from the amorphous to the crystalline state. Results have been analyzed on the basis of the competition between two nucleation mechanisms, one with and the other without foreign species present.